The Influence of Dispersant PAMA on Soot Handling, Wear and Fuel Economy in Heavy Duty Diesel Oils 2003-01-1959
Global Heavy Duty Diesel engine emission legislation requires stepwise reduction of NOx and particulate emissions between 1989 and 2009. Today, most US diesel engine manufacturers are incorporating cooled Exhaust Gas Recirculation (EGR) and retarded engine timing as a means of reducing NOx emission. This has resulted in higher levels of soot being present in used oils.
The first part of this paper builds on previous work with fresh oils and describes a study of the effect of highly sooted oils on low temperature pumpability in diesel engines. Experimental SAE 15W-40 Heavy Duty Diesel Oils (HDDO), formulated with different Viscosity Index Improver (VII) chemistries, were run in a Mack T-8 engine to obtain a soot level of approximately 6.5%. These sooted oils were then evaluated in a Cummins M11 engine installed in a low temperature chamber. Times to lubricate critical engine components were measured at temperatures ranging between -10 °C and -20 °C.
The next step necessary to comply with emission limits from 2004 onwards will be the introduction of catalytic converters, particulate traps and/or selective catalytic reduction (SCR). There is common understanding within the industries, that ash-, sulfur- and phosphorous-containing components are harmful to these exhaust gas after-treatment technologies, and alternative HDDO formulation components are therefore being studied.
The second part of the paper presents results of a study of the effect of different anti-wear components. Experimental diesel engine oils, formulated with conventional zinc dialkyl dithio phosphate (ZDDP) and new additives with anti-wear properties have been tested in a shortened, in-house version of the CEC test OM 602A. Camshaft wear and used oil analyses of the different formulations are compared.
Fuel saving becomes, more and more, a required attribute of state-of-the-art engine oils. The third part of the paper compares fuel savings results of SAE 5W-30 HDDO, formulated with different VIIs, obtained from different diesel engine fuel economy tests.